/*
 * Copyright 2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.batch.integration.x;

import java.util.HashMap;
import java.util.Map;

import org.springframework.batch.core.StepExecution;
import org.springframework.batch.core.partition.support.Partitioner;
import org.springframework.batch.item.ExecutionContext;


/**
 * Takes the result of an (S)FTP Gateway LS (list of FileInfo) and creates a {@link StepExecution} for each file.
 * 
 * Invokes the gateway flow via {@link Gateway}.
 * 
 * @author Gary Russell
 */
public class RemoteFilePartitioner implements Partitioner {

	private final Gateway gateway;

	private final String remoteDirectory;

	public RemoteFilePartitioner(Gateway gateway, String remoteDirectory) {
		this.gateway = gateway;
		this.remoteDirectory = remoteDirectory.endsWith("/") ? remoteDirectory : (remoteDirectory + "/");
	}

	@Override
	public Map<String, ExecutionContext> partition(int gridSize) {
		Map<String, ExecutionContext> partitions = new HashMap<String, ExecutionContext>();
		String[] filesToFetch = gateway.filesToFetch(this.remoteDirectory);
		for (String fileName : filesToFetch) {
			ExecutionContext context = new ExecutionContext();
			context.putString("filePath", remoteDirectory + fileName.trim());
			partitions.put(fileName.trim(), context);
		}
		return partitions;
	}

	public interface Gateway {

		String[] filesToFetch(String remoteDir);
	}

}
